Integrated circuits (IC's) are usually manufactured using lithography. A patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern corresponding to an individual layer of the IC, and this pattern can be imaged onto a target portion (e.g. comprising part of, one or several dies) on a substrate (e.g. a silicon wafer) that has a layer of radiation-sensitive material (resist). In general, a single substrate will contain a network of adjacent target portions that are successively exposed.
Typically, a multiplicity of layers are provided on a substrate, each layer being processed to permanently fix the pattern in that layer before the next layer is formed. Once all of the layers have been formed and processed, the substrate is cut up into individual IC's and each IC is mounted on a board. Each board is provided with legs which are electrically connected to the IC, thereby allowing electrical signals to pass to and from the IC.
It has been conventional to use wires to connect an IC to a board. However, in recent years the distance between locations to which wires are to be bonded has become progressively smaller, and it has been more difficult to use wire bonding. A process which is known as flip-chip bumping is increasingly used to connect IC's to boards instead of using connection wires. In flip-chip bumping, a small amount of material, such as solder or other metal (e.g., gold), is provided at specific locations on each IC on a substrate. The substrate is inverted and bonded to a board, by heating the material such that it melts and then allowing it to cool again. A problem which arises when using flip-chip bumping is that it may be difficult and/or time consuming to determine the locations of the IC's on the substrate (which is used in order to determine exactly where the small amount of material is to be located on the substrate).